Access from Narita Airport to Shibuya!

By Train
Take the Narita Express to Tokyo Station or if available directly Shibuya.
In Tokyo Station, change to JR Yamanote line (green line) direction Shibuya and get off Shibuya

By Bus
After customs, go into the arrival hall and check for a stall with orange panels "Limousine bus".
Book a limousine bus to Shibuya in the link below.
Airport Limousine -> http://www.limousinebus.co.jp/en/

You can find more details in Airport official website.
Narita International Airport -> http://www.narita-airport.jp/en/index.html

After getting off at Shibuya station, you can find the famous and super crowded Shibuya Crossing!!
...Though you should go through a labyrinth before that as Shibuya station, which is under ever lasting construction.

Enjoy your stay in Tokyo!